1. Field of the Invention
This invention relates to an improved process for producing ethanol from methanol by reacting a mixture of methanol and cobalt catalyst, under a carbon monoxide atmosphere, with a gaseous mixture of carbon monoxide/hydrogen.
2. Brief Description of the Prior Art
Ethanol is a well-known organic chemical and has a wide variety of industrial applications including use as a solvent for resins, fats and fatty acids and serves as a "building block" for the synthesis of a variety of larger molecular weight organic compounds.
The overall process of converting an organic compound to a higher homologue, by increasing the number of CH.sub.2 units by one, is termed in the art, "homologation".
Processes for homologating methanol to ethanol are known in the art and provide a potential basis for the synthetic production of ethanol to supplement ethanol obtained by fermentation.
The reference Science, Vol. 113, pp. 206-207 (1951), describes the reaction of methanol and dicobalt octacarbonyl with a 1:1 molar mixture of carbon monoxide/hydrogen at a pressure in the range from 2410 to 5100 psi gauge and a temperature of about 183.degree. to 185.degree. C. A 77% methanol conversion was achieved with only a 38% selectivity towards ethanol. However, higher selectivities are required, for example of above about 45%, before such a process is seriously considered to be commercially attractive.
Other prior art processes, as exemplified in British Pat. No. 951,506 (1964), U.S. Pat. No. 3,248,432 (1966), U.S. Pat. No. 3,285,948 (1966) and Belgian Pat. No. 842,430 (1966), utilize secondary promoter reagents such as iodine, phosphorus compounds, ruthenium and osmium halides and tertiary phosphine for increasing the selectivity of ethanol production during the homologation of methanol. However, these secondary promoter reagents usually increase the cost of such a process and may introduce complicating factors into the ethanol isolation and purification steps.